Buggy code:
@ UiField Label lbllearningAndInnovationText ; @ UiField Label lblAudienceText ; @ UiField Label lblInstructionalmethodText ; @ UiField AssessmentsPlayerStyleBundle playerStyle ; private CollectionDo collectionDo = null ; private Anchor usernameAnchor = null ; private String languageObjectiveValue = null ; public static final String STANDARD_CODE = "code" ; public static final String STANDARD_DESCRIPTION = "description" ; public static final String YUMA_COUNTY_SCIENCE = "YumaCountyScience" ; public static final String YUMA_COUNTY_MATH = "YumaCountyMath" ; public static final String YUMA_COUNTY_SS = "YumaCountySS" ; public static final String YUMA_COUNTY_ELA = "YumaCountyELA" ; public static final String YUMA_COUNTY_PD = "YumaCountyPD" ; private MessageProperties i18n = GWT . create ( MessageProperties . class ) ; private static AssessmentsMetadataWidget . MetadataWidgetUiBinder uiBinder = GWT . create ( AssessmentsMetadataWidget . MetadataWidgetUiBinder . class ) ; interface MetadataWidgetUiBinder extends UiBinder < Widget , AssessmentsMetadataWidget > { } public AssessmentsMetadataWidget ( ) { } public void setCollectionMetadata ( CollectionDo collectionDo ) { } public void setUserName ( String userName ) { } public void setViewCount ( String viewCount ) { } public void setUserProfileImage ( String profileUserId ) { } @ UiHandler ( "profileThumbnailImage" ) public void setDefaultProfileImage ( ErrorEvent event ) { } public void renderCourseInfo ( List < String > courseInfo ) { } public List < Map < String , String > > getStandardsMap ( List < StandardFo > standareds , boolean isStandards ) { } public void renderStandards ( FlowPanel standardsContainer , List < Map < String , String > > standardsList , boolean isStandards ) { } public void renderLanguageObjective ( String languageObjective ) { } public void renderDepthOfKnowledge ( List < checkboxSelectedDo > depthofKnowledgeList ) { } public void renderInstructionalMethod ( List < checkboxSelectedDo > instructionmethodList ) { } public void renderAudience ( List < checkboxSelectedDo > audienceList ) { } public void renderLearningAndInnovationSkill ( List < checkboxSelectedDo > learningSkillsList ) { } @ UiHandler ( "seeMoreAnchor" ) public void clickSeeAll ( ClickEvent event ) { } public void setTeacherName ( String userNameDisplay , String profileImageUrl ) { } public class TeacherImage extends Composite { private Image image = null ; private String teacherImageUrl = "" ; public TeacherImage ( String imageUrl ) { } public void onLoad ( ) { } public class TeacherErrorEvent implements ErrorHandler { @ Override public void onError ( ErrorEvent event ) { } } } public static String convertMillisecondsToDate ( Long milliseconds ) { } public void setDirectionText ( String text ) { } public void setLabelAndIds ( ) { lblAuthor . setText ( i18n . GL0573 ( ) ) ; lblAuthor . getElement ( ) . setId ( "lblAuthor" ) ; lblAuthor . getElement ( ) . setAttribute ( "alt" , i18n . GL0573 ( ) ) ; lblAuthor . getElement ( ) . setAttribute ( "title" , i18n . GL0573 ( ) ) ; lblCourse . setText ( i18n . GL0574 ( ) ) ; lblCourse . getElement ( ) . setId ( "lblCourse" ) ; lblCourse . getElement ( ) . setAttribute ( "alt" , i18n . GL0574 ( ) ) ; lblCourse . getElement ( ) . setAttribute ( "title" , i18n . GL0574 ( ) ) ; lblStandards . setText ( i18n . GL0575 ( ) ) ; lblStandards . getElement ( ) . setId ( "lblStandards" ) ; lblStandards . getElement ( ) . setAttribute ( "alt" , i18n . GL0575 ( ) ) ; lblStandards . getElement ( ) . setAttribute ( "title" , i18n . GL0575 ( ) ) ; lblcentury . setText ( i18n . GL3199 ( ) ) ; lblcentury . getElement ( ) . setId ( "lblCenturys" ) ; lblcentury . getElement ( ) . setAttribute ( "alt" , i18n . GL3199 ( ) ) ; lblcentury . getElement ( ) . setAttribute ( "title" , i18n . GL3199 ( ) ) ; <START_BUG> previewFlagButton . setText ( i18n . GL0556 ( ) ) ; <END_BUG> previewFlagButton . getElement ( ) . setId ( "lnkPreviewFlagButton" ) ; previewFlagButton . getElement ( ) . setAttribute ( "alt" , i18n . GL0556 ( ) ) ; previewFlagButton . getElement ( ) . setAttribute ( "title" , i18n . GL0556 ( ) ) ; previewFlagButton . removeStyleName ( INSTANCE . getPlayerStyle ( ) . previewCoverFlagImageOrange ( ) ) ; previewFlagButton . setStyleName ( INSTANCE . getPlayerStyle ( ) . playerPreviewCoverFlagImage ( ) ) ; lbllanguageObjectiveText . setText ( i18n . GL1721 ( ) ) ; lbllanguageObjectiveText . getElement ( ) . setId ( "lblLanguageObjectiveText" ) ; lbllanguageObjectiveText . getElement ( ) . setAttribute ( "alt" , i18n . GL1721 ( ) ) ; lbllanguageObjectiveText . getElement ( ) . setAttribute ( "title" , i18n . GL1721 ( ) ) ; teacherContainer . getElement ( ) . setId ( "pnlTeacherContainer" ) ; classInfoPanel . getElement ( ) . setId ( "pnlClassInfoPanel" ) ; lblClassInfo . getElement ( ) . setId ( "lblClassInfo" ) ; lblclassTitle . getElement ( ) . setId ( "lblClassTitle" ) ; classTitleValue . getElement ( ) . setId ( "lblClassTitleValue" ) ; teacherPanel . getElement ( ) . setId ( "pnlTeacherPanel" ) ; lblTeacher . getElement ( ) . setId ( "lblTeacher" ) ; teacherProfileContainer . getElement ( ) . setId ( "pnlTeacherProfileContainer" ) ; teacherNameLabel . getElement ( ) . setId ( "lblTeacherNameLabel" ) ; dueDateSection . getElement ( ) . setId ( "pnlDueDateSection" ) ; lbldueDate . getElement ( ) . setId ( "lbldueDate" ) ; dueDate . getElement ( ) . setId ( "lbldueDateLabel" ) ; directionSection . getElement ( ) . setId ( "pnlDirectionSection" ) ; lblDirections . getElement ( ) . setId ( "lblDirections" ) ; lblDirectionsDesc . getElement ( ) . setId ( "lblDirectionsDesc" ) ; authorPanel . getElement ( ) . setId ( "pnlAuthorPanel" ) ; profileThumbnailImage . getElement ( ) . setId ( "imgProfileThumbnailImage" ) ; userNameLabel . getElement ( ) . setId ( "lblUserNameLabel" ) ; teamContainer . getElement ( ) . setId ( "fpnlTeamContainer" ) ; courseSection . getElement ( ) . setId ( "pnlCourseSection" ) ;

Fix:
previewFlagButton . setText ( i18n . GL3493 ( ) ) ;